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Does multiverse really explain fine-tuning?

  1. Aug 22, 2015 #1
    Hello everyone,

    I am not sure about this issue and this is the reason why I am asking this question. I can write many sentences on this topic, but I will try to make my point as short is possible.

    I will suppose you are familiar with multiverse idea and anthropic principle..

    My question is: Lets suppose there are billions and billions of other universes, does that solve problem of fine-tuning? Wouldn't there still have to be some fundamental laws which creates universes in multiverse- in other words, wouldn't there have to be "multiverse generator" which would have to be fine-tuned "for creating other universes with different constants"... Am I missing something, or with multiverse theory problem is not solved, just pushed one step further?
     
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  3. Aug 22, 2015 #2

    mfb

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    There is no fine-tuning involved in this part, because the creation of universes can be very general. You don't need to be a good darts player to hit random spots on the wall with each attempt, but you have to be good to hit the bullseye with one attempt.
     
  4. Aug 22, 2015 #3

    atyy

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  5. Aug 22, 2015 #4
    But you still need a mechanism which would throw the arrows... If I get this right, the mechanism is eternal inflation, which will produce the universes forever-infinite number of universes..

    But what if there is no infinite number of universes? What if there is no such thing as eternal inflation, and at one point, inflation have to stop... Lets suppose there is finite number of universes, and if there is no enough universes to cover "fine-tuning of our universe" then the multiverse theory, would not solve the problem of fine-tuning.. Is that correct?
    I am not challenging anything or anybody, as you can see, english is not my native language( I am sorry for my grammar mistakes) and I am not physicist... But there are some ideas, which would make eternal inflation impossible, so because of that I am asking the question...
    https://www.newscientist.com/article/mg22229692-600-quantum-twist-could-kill-off-the-multiverse/
     
    Last edited: Aug 22, 2015
  6. Aug 22, 2015 #5
    The Anthropic Principle seems neater.


    fine-tuning is a semi-religious statment. We are a product of the universe, so we should not be suprised that the universe looks the way it does.
     
  7. Aug 22, 2015 #6

    atyy

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    But it is a good religion. Its philosophy is that all our theories are wrong, and not the final theory. If we knew the true final theory, then we wouldn't be surprised if it is fine tuned, since the true ultimate reality is simply what it is.

    One technical way of stating this religion is via Wilsonian renormalization.
     
  8. Aug 23, 2015 #7

    Orodruin

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    A number of posts have been deleted, please keep to the original topic given by the OP about fine tuning and the multiverse.
     
  9. Aug 23, 2015 #8

    mfb

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    Right, but this mechanism does not have to be fine-tuned. It just has to exist.
     
  10. Aug 23, 2015 #9

    Chalnoth

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    Yes. Multiverse theories typically have a mechanism for the production of a large number of regions like the one we live in. Eternal inflation is one such mechanism that has been proposed.

    Also, multiverse theories can only explain fine tuning if that fine tuning is necessary for any observers to exist. That's often not very easy to demonstrate.
     
  11. Aug 23, 2015 #10

    mfb

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    If there is no fine-tuning necessary there is no need to explain fine-tuning.
     
  12. Aug 23, 2015 #11
    You are right, the multiverse just pushes the problem one step further. That's what scientists do. It keeps them busy and off of drugs.

    More specifically, it obviates fine tuning of physical constants, but it doesn't explain how the whole situation came to be in the first place. But who knows? You've got to take these things one step at a time.
     
  13. Aug 23, 2015 #12
    The multiverse generator might be eternal inflation or the many worlds of Qm, or maybe a cyclic universe with different constants in each cycle. Or maybe one universe with varying constants in it. i dont see why these have to be fine tuned. They may or may not be true.
     
  14. Aug 23, 2015 #13

    Chronos

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    The multiverse does one thing very well, it explains observations that appear random or improbable, like the values of physical constants. Under most multiverse theories, all possible values for physical constants, and combinations thereof, are realized somewhere in the multiverse. We just happen to reside in one that has the particular values we measure. This yields a satisfyingly high probability [100%] a universe like ours exists - reducing our reality to an anomolous statistic and disincentivizes scientific inquiry .
     
  15. Aug 24, 2015 #14

    Drakkith

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    Sounds pretty boring.
     
  16. Aug 24, 2015 #15

    Garth

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    I always say that a theory that can explain anything and everything explains nothing - boring indeed.

    Garth
     
  17. Aug 24, 2015 #16

    stevendaryl

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    On the other hand, it seems that we should be open to the possibility that some facts may have no non-boring explanation.
     
  18. Aug 24, 2015 #17

    Chalnoth

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    It is certainly possible for apparent fine tuning to be explained by as-yet-unknown physical laws creating relationships between different parameters. But there's also no reason to believe such explanations exist if the apparent fine tuning is necessary for any observers to exist.

    We may eventually be forced to conclude that there is no explanation for such apparent fine tuning except that the fundamental laws are prolific and certain pieces of apparent fine tuning are necessary for observers.
     
  19. Aug 24, 2015 #18

    Haelfix

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    Indeed the question "why are planetary orbits fine tuned for life" is answered in just such a manner. There is no deeper mechanism at play for selecting earth like planets in the Goldilocks zone. As best we can tell, it's purely a matter of having large ensembles and the anthropic principle.
     
  20. Aug 25, 2015 #19

    Chronos

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    The mulitverse 'expains' everything. It eliminates the need for scientiific inquiry. It is little better than a rartional version of theology, You merely replace your deity of choice with probabilities.
     
    Last edited: Aug 25, 2015
  21. Aug 25, 2015 #20

    Chalnoth

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    This is completely false and you should be aware of that fact. Many specific multiverse models have testable predictions. Some are incomplete or poorly constructed and make no predictions, but that shouldn't poison the entire paradigm.

    It's really sad that so many dismiss multiverse models out of hand simply because they make them uncomfortable.
     
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